Robust and ultrathin pore‐filling anion exchange membranes for water electrolysis

Abstract Ultrathin and robust composite anion exchange membranes are developed by infiltrating poly(biphenyl piperidinium) solution into PE porous substrate and overcoming the poor wettability of the PE substrate in a pore‐filling procedure. By strengthening the binding between ionomers and the porous substrate via a physical interlocking strategy, symmetric and dense composite membranes were developed. A representative membrane, namely PE‐PBP‐30%, displays a tensile strength exceeding 118 MPa, an elongation at break around 87%, and maintains H 2 permeability as low as 1.85 Barrer at 2 bar. Anion exchange membrane water electrolysis (AEMWE) based on the PE‐PBP‐30% could be operated at a current density of up to 800 mA/cm 2 at 1.8 V and demonstrates stable performance at 500 mA/cm 2 and 60°C for 600 h with a voltage increase rate of 0.25 mV/h. This study explores the possibility of combining traditional homogeneous AEMs with diaphragm membranes for AEMWE and provides insights into the development of AEMWEs using pore‐filling membranes.